Fireproofing textiles and the like



2,907,683 i p FIREPROOFING TEXTILES AND THE LIKE Raymonde Genevieve Madeline, ne, Madeline, and Jean Francois Pathus-Labour, Paris, France, assignors to Firma Deutsche Erdoel A.G., Hamburg, Germany N'o-Dra'wing. Application February 8, 1954 Serial No. 408,998

i 2 Claims. or. 117-136) The present invention relatesto. the fireproofing of textiles and the like materials and to novel-fireproofed textile. materials. r

It is an object of the present invention to provide a process of fireproofing textile materials so as to render the samenon-inflammable and incapable of supporting combustion. I t t t It is another'object of the present invention to provide novel textile'and the like materials such as paper, .synthetic fiber materials, and the like impregnated with a novel fireproofing material.

Other objects and advantages of the present invention will be apparentfrom a: further reading. of the: specification. and .ofthe appended claims.

Thepresent invention has as an. object thereof. a process of treating, textile fabrics of all. types to hygroscopical- .ly condition the fabric in view of impregnating the same so as. to render the substances treated according to the process of the present invention inflammable and incapable of supporting. combustion and further being able to resist deterioration at high temperatures as well upon contact with flame and gases at high temperature.

It is known that the effect of fireproofing as well as the thermal insulation effect is a function of'the coeflicient of thermal conduction of the impregnant and of the substance impregnated. t t

The process of the present invention consists in impregn'ating the textile fabric of all types'of materials such asgarments, sacks or other packing materials with an aqueous solution of a derivative of alginic acid. Alginic acid is a high polymer of d-mannuronic acid.

, The. impregnant is. then transferred into an. insoluble which-because of the properties which will be later described prevents the thus treated textile material from burning.

The water-soluble alginic acid derivative in a solution ofwhich the textile fabric is immersed or otherwise contacted. is preferably an alkali metal salt. of alginic acid, an ammonium salt of alginic acid, an amine of alginic acid, an, ester of alginic acid or an ether of alginic acid. Itis further preferred that the aqueous solution contain about 0.5-5 and preferably 1'2%' ofthe soluble alginicacid derivative.

The. precipitation of. the insoluble alginic acid derivative is preferably accomplished by treatment with a watersoluble heavymetal salt such as. the hygroscopic salt calcium chloride. Thisheavy metal salt reacts with the sol- 'uble. alginic acid. forming an insoluble heavy metal salt of. alginic acid.. The useful heavy metal salts are those such as. soluble salts of iron, zinc, copper, lead, etc. It is preferable that soluble alkali earth salts such as calcium chloride be used forthis purpose and it is further preferable that an excess of calcium chloride be used in precipitating the insoluble derivative of alginic acid.

r 2,907,683 Patented Oct. 6, 1959 Some Ofthfi excess of calcium chloride remains in the textile material after it has been allowed to dry substantially and this calcium chloride due to its hygroscopic properties prevents the material from drying completely.

It is another preferred embodiment of the present in,- vention that the insoluble derivative of alginic acid be precipitated by the action of an acid-forming gas or by the action of a solution of an acid. Such acid-forming gases include hydrogen chloride, hydrogen bromide, hydrogen iodide, etc. The term acid-forming gas as used herein refers to those gases which in water solution form acids. Acids which may be used with the present invention includehydrochloric acid, hydrobromic acid, acetic acid, propionic acid, etc.

It. is still another preferred embodiment of the present invention that'either the impregnating solution or the precipitating: means contain a water soluble hygroscopic substance such'as apolyfunctional alcohol or derivative thereof. This. hygroscopic substance is impregnated along with the insoluble alginic acid derivative, into the material and it.thereby prevents the material from completely drying out. i

The soluble salts of alginic acid include alkali metal salts, ammonium salts, amine salts, etc., i.e. sodium alginate, potassium alginate, ammonium alginate and the like. The soluble ethers and esters of alginic acid include methyl, ethyl, acetyl alginic acid and the like. These derivatives are very similar to salts of alginic acid. However the salts are more preferable with the the present invention for reasons of economy.

The treatment with the substance which causes formation of an insoluble derivative of alginic acid causes an impregnation into the pores of the material with thein soluble derivative, or a layer is formed over the surface of the material thereby coating the same. The thus treated material is mechanically very strong and is practically impermeable to liquids and gases.

The soluble salts of the heavy metals named above include iron chloride, copper sulfate, lead acetate, etc. These salts may be applied in solid state to the impregnated solution, being therein dissolved by the water of said solution and reacting in said solution with the soluble alginate to form an insoluble heavy metal derivative of alginic acid. It is however preferable to use a solution of such heavy metal salt so as to facilitate this reaction. It. is also possible to use water soluble alkali earth salts either in solid form or in solution. These alkali earth salts react with the soluble alginate to form an insoluble alkali earth derivative of alginic acid. The soluble alkali earth salts which may be used include, though are not limited to, calcium chloride, strontium nitrate, barium acetate, etc.

The strength of the impregnating layer depends partly on the amount of water given up by the gel through syneresis. The syneresis is to an extent controllable by the concentration, temperature and time of action of the precipitating solution. It is further dependent of course upon the concentration and extent of polymerization of the alginic acid derivative.

To increase the plasticity and elasticity of the impregnation and to prevent this impregnation from completely drying out it is favorable to include a water soluble agent such as glycerine, glycol, glycol ether, etc. in either the impregnated solution or in the precipitating solution.

The exceptional characteristics of the thermal insulation of the insoluble alginic acid derivative with which the material is impregnated according to the present invention will be apparent from the following description, these characteristics allowing for the attainment of. the objects of the present invention.

The attempt to provide fireproof materials have not been very successful and it is known that not only must properties:

the material itself be protected but the objects nearby must also be protected from the flames.

Asbestos cloth has been utilized to provide such protection, but the use of such cloth is both difficult and expensive] 1* '1 By the present invention, on the other hand, ;a cloth or fabric is utilized which is treated-by immersion in a fireproofing solution. For this purpose one utilizes a material which will serve to support the fireproofing substance, such as jute, paper, threads, synthetic fibers, cotton, and all other substances, of which the web 'may attain the dimensions of 3 mm. x 3 mm. and wherein the dimensions may vary according to. the use to which the material is put.

The impregnation according to the process ismade as above described. According to the'present invention an agent which has resistance. to fire may be: included-in the impregnation such as a silicious'substance, silicoalumina, magnesi-a alumina, white clay," asbestos, mica, etc. Preferably, hydrated magnesium silicate is utilized (Mg (SiO .H O). The amount of the fireproofing ad- 'ditive such as hydrated magnesium silicate may vary within relatively wide limits, though preferably the amount is between 0.25-3% by weight.

The essential physical characteristics of the mixture of the alginate and the fireproofing additive are as follows:

The hydrated magnesium silicate is nobfusible to straw and its resistance to fire is often utilized, however,

the inconvenience of utilizing such substance is that it dries'very rapidly and thus loses its properties. This inconvenience is overcome by the combination of the substance with the alginate impregnation of the present invention. 7

In eifect the precipitation reaction, as pointed out above is most favorably attained by means of a hygroscopic salt such as calcium chloride in very concentrated solution. As an example, the impregnation of 1 square meter of a material contains the following:

20 g. calmium alginate 10 g. hydrated magnesium silicate 350 g. calcium chloride 1 kg. water It should be noted that the efiicacy of the absorption and the desorption of the humidity by the insoluble alginate composition permits theattainment of a great number of applications of the products, for example for special packing purposes.

The impregnations according to the pres t invention give the materials impregnated therewith, the following (1) Complete impermeability to gas, preventing the access of oxygen of the air to everything contained within the material treated, v

(2) The water retained by the hygroscopic properties of the layer of impregnant has a low vapor tension and resists heat for a long time, the absorption 'of calories to include in the bath in which the insoluble alignate impregation is produced, antiseptic products such as sodium benzoate, formaldehyde, or phenol derivatives so as to assure preservation.

The following examples are given as illustrative of methods of applying the impregnation and the results of different materials so impregnated.

Example I treated sack is then further treated with a 40% solution of calcium chloride, i.e. through immersion in such solution, for about 5 minutes. After removing the sack from the calcium chloride solution it is allowed to drain for about an hour so that the major quantity of water is forced out through syneresis. The sack is thus impregnated with a film-of calcium alginate which rendersthe sack fireproof.

i Example II A sack made'of paper having fine pores, is immersed in a 1 solution of sodium alginate to which 5% glycol has been added. This sack is then treated with a solution of hydrochloric acid, likewise containing 5% glycol, for 5 minutes. After a few hours or even after a few days, the sack may be utilized, the impregnating layer remaining elastic even under heat and'the sack being substantially fireproof.

Example [11' 1 Two stacks of straw are laid side by side. 'A first stack is covered with a sheet of jute impregnated with calcium alginate according to the present invention, "and the other stack is covered with a' non-impregnated sheet of jute. Both'stacks of straw are subjected toan'in cendiary blast. The second stack of strawburnsicompletely including the sheet of jute cov 'eringthe same, while the first stack of straw remains protected from the flames and the fire does not spread thereto.

Example I stack of straw is completely covered with a textile A fire is started in a field under conditions corresponding to a fire which might start at harvest time. After the fire has extended somewhat in the field, a net impregnated as in Example I or II is spread-aroundthe fire. The flames stop at the border of the cloth. After several lflsrlgls the fire becomesextinguished since it cannot pass r v M n Example VI I Balls of cotton or'artificial textile are enveloped in fabric impregnated with an insoluble alignate and are placed side by side with similar balls prepared" according to the usualmethods but not covered with' 'a protecting sheet. A fire is started simultaneously about both the covered and the non-covered cotton or synthetic fiber balls. In the non-covered balls the fire rapidly reaches the periphery of the balls and the fiames then attack'th'e center. In a short time the cotton balls are completely enveloped by flame. On the other hand the cotton or artificial textile fiber balls covered with the alginateimpregnated textile retain suificient humidity because of the hygroscopic coating to render combustion extremely difiicult and the same do not burn.

Example VII Example VIII Q 1 999. 9 leaves are rolled into balls of usual dimension i.e. 1.5 m. high and 2 m. wide and are then enveloped in a cloth impregnated according to the present invention. This tobacco is completely protected from any danger of fire while retaining the humidity in the tobacco.

Example IX Dried fruits are put in a sack impregnated with an insoluble alginate according to the present invention. The humidity of the fruit is retained while protecting the same from danger of fire.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence.

What is claimed as new and desired to be secured by Letters Patent is:

1. A process of fireproofing textile materials, comprising the steps of applying to a textile material an aqueous impregnating solution containing at least one water-soluble compound selected from the group consisting of salts and esters of alginic acid; treating the thus-applied impregnating solution with an excess of hygroscopic calcium chloride so as to precipitate from the thus applied impregnating solution a Water insoluble derivative of alginic acid which adheres to said textile material and forms a substantially gas impermeable impregnation preventing said thus impregnated textile material from burning; and allowing the water to drain from the thus impregnated textile material so as to remove the major portion of the water therefrom, said excess of said hygroscopic calcium chloride binding water to said Water insoluble alginic acid impregnation and preventing complete drying of the thus impregnated textile material, thereby obtaining an impregnated textile material which is substantially gas impermeable and highly resistant to burning and which remains elastic and non-brittle due to said bound water.

2. A process of fireproofing textile materials, comprising the steps of applying to a textile material an aqueous impregnating solution containing water-soluble sodium alginate; treating the thus applied impregnating solution with an excess of hygroscopic calcium chloride so as to precipitate from the thus applied impregnating solution water insoluble calcium alginate which adheres to said textile material and forms a substantially gas impermeable impregnation preventing said thus impregnated textile material from burning; and allowing the water to drain from the thus impregnated textile material so as to remove the major portion of the water therefrom, said excess of said hygroscopic calcium chloride binding water to said water insoluble calcium alginate impregnation and preventing complete drying of the thus impregnated textile material, thereby obtaining an impregnated textile material which is substantially gas impermeable and is highly resistant to burning and which remains elastic and non-brittle due to said bound water.

References Cited in the file of this patent UNITED STATES PATENTS 1,321,708 Bradley Nov. 11, 1919 2,387,865 Van Kleeck Oct. 30, 1945 2,435,701 Vallandigham Feb. 10, 1948 2,436,181 Rosser Feb. 17, 1948 2,513,416 Gloahec July 4, 1950 2,568,850 Fasold et a1 Sept. 25, 1951 2,610,957 Steinman et al Sept. 16, 1952 FOREIGN PATENTS 27,606 Great Britain 1898 572,790 Great Britain Nov. 19, 1942 625,609 Great Britain June 30, 1949 

1. A PROCESS OF FIREPROOFING TEXTILE MATERIALS, COMPRISING THE STEPS OF APPLYING TO A TEXTILE MATERIAL AN AQUEOUS IMPREGNATING SOLUTION CONTAINING AT LEAST ONE WATER-SOLUBLE COMPOUND SELECTED FROM THE GROUP CONSISTING OF SALTS AND ESTERS OF ALGINIC ACID; TREATING THE THUS-APPLIED IMPREGNATING SOLUTION WITH AN EXCESS OF HYDROSCOPIC CALCIUM CHLORIDE SO AS TO PRECIPITATE FROM THE THUS APPLIED IMPREGNATING SOLUTION A WATER INSOLUBLE DERIVATIVE OF ALGINIC ACID WHICH ADHERES TO SAID TEXTILE MATERIAL AND FORMS A SUBSTANTIALLY GAS IMPERMEABLE IMPREGNATION PREVENTING SAID THUS IMPREGNATED TEXTILE MATERIAL FROM BURNING; AND ALLOWING THE WATER TO DRAIN FROM THE THUS IMPREGNATED TEXTIEL MATERIAL SO AS TO REMOVE THE MAJOR PORTION OF THE WATER THEREFROM, SAID EXCESS OF SAID HYGROSCOPIC CALCIUM CHLORIDE BINDING WATER TO SAID WATER INSOLUBLE ALGINIC ACID IMPREGNATION AND PREVENTING COMPLETE DRYING OF THE THUS PREGNATED TEXTILE MATERIAL, THEREBY OBTAINING AN IMPREGNATED TEXTILE MATERIAL WHICH IS SUBSTANICALLY GAS IMPERMEABLE AND HIGHLY RESISTANT TO BURNING AND WHICH REMAINS ELASTIC AND NON-BRITTLE DUE TO SAID BOUND WATER. 